Traditionally, maintenance indicators in a vehicle utilize sensors for indicating operating parameters relating to materials required to operate the engine. For example, a fuel level in automobile fuel tanks is determined using a fuel level sensor having an elongated rod with a free end supporting a float which moves along with changes in fuel levels. The other end of the rod is pivotally mounted to an indicating mechanism typically including an elongated electrical resistance grid and a contact pad which moves with movements of the float and the rod as the fuel level changes. The movement of the contact pad along the resistance grid changes electrical characteristics of the indicating mechanism providing a variable input to a fuel indicator gauge located within a passenger compartment of a vehicle.
However, in a moving vehicle, fuel level values measured by fuel level sensors may be inaccurate due to driving conditions, such as acceleration or deceleration causing the fuel sloshing movement, or uphill and downhill driving. The need thus exists for a sensorless fuel level indicator able to determine a fuel level regardless of driving conditions.
Typical engine oil change indicators produce indications that engine oil should be changed based on measurements carried out by a combination of sensors for detecting various oil parameters, such as pressure, temperature, transparence, resistivity, etc. However, these indicators are complicated and costly. Therefore, it would be desirable to provide an oil change indicator that does not require an expansive sensing arrangement for detecting engine oil parameters.